For example, cut limbs and timbers from thinning, which are generated when cutting down trees in forests and trimming the trees, branches generated with land development, green tract maintenance, etc., and scrap woods having been used in broken-down wooden houses are usually finally discarded as industrial wastes. A wood crusher is employed in such a waste treating process to crush target woods into predetermined sizes at the work site before transport for the purpose of, e.g., reducing the volume of the crushed woods as wastes, or breaking the crushed woods into wood chips and fermenting the chips for reuse as organic fertilizer.
That type of wood crusher comprises a crushing rotor including crushing bits disposed in an outer peripheral portion of the rotor, a sieve member disposed around such a crushing apparatus, a sieve member holding means (support member) for holding the sieve member in a position around the crushing apparatus, and a moving mechanism for moving the sieve member holding means to a position where the sieve member is replaced (see, e.g., Patent Document 1). In that wood crusher, target woods are crushed by the crushing bits provided on the crushing rotor. When the crushed woods (wood chips) are broken into pieces smaller than an area of each of many openings formed in the sieve member, those wood chips are discharged to the exterior through the openings. Because the grain size of the crushed woods is decided substantially depending on the opening area of the sieve member, an adjustment of the grain size of the crushed woods is performed by preparing plural kinds of sieve members and replacing one sieve member with another as required. The replacement of the sieve member is performed by moving the sieve member holding means with the aid of the moving mechanism to a position where the sieve member is replaced, and mounting the desired sieve member after dismounting the current one. The moving mechanism comprises a sling bolt and a support member (shaft member) which is disposed at one end of the sieve member holding means rotatably supported by a bracket and which is screwed with the sling bolt for supporting the sieve member holding means at a predetermined position. When the sling bolt is rotated, the support member screwed with the sling bolt is vertically moved in response to the rotation of the sling bolt. As a result, the sieve member holding means is turned with the other end thereof serving as a pivot axis so that the sieve member is moved to the replacement position.
Patent Document 1: JP, A 2002-346418